SPC Aug 19, 2026 1300 UTC Day 1 Convective Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0754 AM CDT Wed Aug 19 2026

Valid 191300Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OZARKS
INTO THE MID MS VALLEY AND SOUTHERN AZ....

...SUMMARY...
Thunderstorms with severe wind gusts and hail will be possible this
afternoon across the mid Mississippi Valley. Isolated severe gusts
and hail will also be possible from the lower to mid Missouri Valley
westward into the Great Plains. A few severe gusts could also occur
in southern Arizona and in the Southeast.

...Mid MO Valley...
Early-morning satellite imagery depicts a low-amplitude shortwave
trough moving through western SD/NE. Showers and thunderstorms are
ongoing downstream of this wave across central/eastern SD and
north-central/northeast NE. Recent surface analysis place a corridor
of moderate low-level moisture (i.e. upper 60s dewpoints) from
eastern NE northwestward to a weak surface low over central SD.
Instability will likely build within this corridor as the shortwave
continues eastward, potential resulting increasing thunderstorm
coverage and intensity later this morning into the afternoon across
eastern NE. Vertical shear will be strong enough for organized storm
structures and the potential for a few supercells. This potential
will be largely dictated by how much the airmass can destabilize
amid the cloud cover and limited heating. Large hail is possible
within the initially more cellular activity, but a transition to a
more linear mode results in damaging gusts becoming the primary
hazard with eastward/southeastward extent.

...Ozarks into the Mid MS Valley...
Regional radar imagery shows a large cluster of showers and
thunderstorms progressing across the region. A few stronger updrafts
are possible within this cluster, but limited buoyancy downstream
and a weakening low-level jet are forecast to result in gradually
diminishing storm strength over the next few hours. The airmass is
forecast to gradually recover in the wake of this cluster, with
strong buoyancy (i.e. MLCAPE over 2000 J/kg) in place by the late
afternoon. The shortwave trough mentioned in the preceding paragraph
is forecast to continue southeastward, and ascent attendant to this
wave coupled with weak low-level convergence along the cold front
will support thunderstorm development within this destabilized
airmass this evening. Strengthening mid-level flow will result in
moderate to strong deep-layer vertical shear supportive of
supercells. Large hail and damaging gusts are the primary hazards,
but a strengthening low-level jet will result in enough low-level
shear to support the potential for a few tornadoes as well. Storms
will tend to cluster with eastward extent, with the threat for
damaging gusts persisting within these bowing line segments.

...Ohio Valley...
A somewhat secondary area of late afternoon/early evening
thunderstorm development is anticipated from central IL into central
IN and central OH. Moderate buoyancy and strong westerly flow aloft
support the potential for isolated supercells capable of large hail
and isolated damaging gusts.

...Central/Southern High Plains...
Surface analysis places 60s dewpoints into the Colorado Foothills
this morning, increasing into the upper 60s farther east/southeast
into southwest KS. Strong heating/mixing of this airmass is
anticipated this afternoon, promoting the development of moderate
buoyancy. Thunderstorm development is expected across the high
terrain before then progressing eastward into the lower elevations.
Moderate northwesterly flow aloft will be support organized storms
structures, and large hail is possible along the Foothill.
Thereafter, a trend towards an outflow-dominant storm mode will
result in strong to severe gusts across portions of the
central/southern High Plains. Higher probabilities may be needed in
later outlooks if guidance continues to indicate increased coverage.


...AZ...
The presence of monsoon moisture will support moderate buoyancy
across the lower elevations of south-central AZ during the late
afternoon. This should allow for storms that develop over the high
terrain to maintain intensity as they process southwestward into the
lower elevations this afternoon/evening. Steep low to mid-level
lapse rates and large temperature-dewpoint spreads will support the
potential for severe gusts.

...Southeast into northern FL...
A very moist airmass (i.e. dewpoints in the 70s) will be in place
today from MS into FL. Strong heating is anticipated, with high
temperatures in the upper 90s across much of the region. As surface
temperatures warm, moderate instability will develop, with scattered
thunderstorms expected amid modest low-level convergence from MS
into western/southern AL and across the FL Panhandle into northern
FL. The deep low-level moisture combined with steep low-level lapse
rates will support an isolated wind-damage threat during the mid to
late afternoon.

..Mosier/Bunting.. 08/19/2026

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